Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The proteins p15 and p24 of the human immunodeficiency virus (HIV) type 1 gag gene were expressed as fusion proteins in Escherichia coli for detecting antibodies against the acquired immunodeficiency virus by Western blot (immunoblot) analysis. These fusion proteins contain amino acids 1 to 375 of the E. coli beta-galactosidase linked to the viral protein(s) by a recognition sequence for the specific protease factor Xa. They are obtained in large amounts in insoluble inclusion bodies. To avoid ambiguous results caused by cross-reaction of sera with bacterial proteins in Western blots, we purified the recombinant fusion proteins and subsequently removed the bacterial part of the fusions by cleavage with factor Xa. The cleavage mixtures were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and blotted onto nitrocellulose membranes. The viral proteins obtained by this method did not contain any bacterial proteins or protein fragments. Thus, false-positive results in HIV Western blot analysis with bacterially expressed HIV proteins can be excluded with these purified recombinant viral antigens.
...
PMID:Cleavage of procaryotically expressed human immunodeficiency virus fusion proteins by factor Xa and application in western blot (immunoblot) assays. 250 57

Attenuated variants of vaccinia virus have excellent potential for the construction of safe recombinant live vaccines. In this investigation, highly attenuated variants of vaccinia virus with several genetic markers and a variant recombinant were tested in Balb/c mice for their ability to induce humoral immune response. Mice primed with variants that had an 8-MDa deletion at the left end of the viral genome induced similar levels of circulating anti-vaccinia antibodies as the wild-type virus. However, mice primed with variants that had several genetic lesions (deletions and point mutations) induced lower levels of circulating anti-vaccinia antibodies. Mice primed and boosted with a recombinant variant with several genetic lesions, and containing the complete envelope gene of the human immunodeficiency virus (HIV) and the bacterial beta-galactosidase (beta-gal) gene, induced significant antibody response to gp 160 and beta-gal. The antibody response to gp 160 was markedly increased by successive inoculations with the recombinant variant. Our findings provide evidence that the extent of activation of the immune system by vaccinia variants can be modulated by the nature of the virus genetic lesion. In addition, when these variants are used as recombinant vaccines, it is possible to induce low levels of circulating anti-vaccinia antibodies after priming and yet achieve significant antibody response to virus-expressed foreign antigens, even after repeated boosters. Such variants could be useful in the design of live recombinant viruses as safe vaccines.
...
PMID:Humoral immune response elicited by highly attenuated variants of vaccinia virus and by an attenuated recombinant expressing HIV-1 envelope protein. 251 Apr 2

Site-directed mutagenesis was used to identify functional domains present within the human immunodeficiency virus (HIV) tat protein. Transient cotransfection experiments showed that derivatives of tat protein with amino acid substitutions either at the amino-terminal end or at cysteine residue 22, 37, 27, or 25 were no longer able to transactivate HIV long terminal repeat-directed gene expression. Incubation of Tat expressed in Escherichia coli with zinc demonstrated that both authentic Tat and cysteine mutation derivatives could form metal-protein complexes. The tat proteins that contained alterations within the cluster of positively charged amino acid residues retained their ability to transactivate gene expression, albeit at markedly reduced levels. Indirect immunofluorescence showed that the authentic tat protein and the amino-terminal and cysteine substitution mutants all localized in the nucleus, with accumulation being most evident in the nucleolus. In contrast, nuclear accumulation was greatly reduced with the basic-substitution mutations. Consistent with this result, a fusion protein that contained amino acids GRKKR, derived from the basic region, fused to the amino-terminal end of beta-galactosidase also accumulated within the nucleus. These results demonstrate that the 14-kilodalton tat protein contains at least three distinct functional domains affecting localization and transactivation.
...
PMID:Structural and functional characterization of human immunodeficiency virus tat protein. 253 18

A gene encoding the human immunodeficiency virus-1 (HIV-1) TAT protein was chemically synthesized and expressed in HeLa cells and in a cell-free system. To facilitate both the assembly of the synthetic gene and further mutagenesis and gene fusion studies, several unique restriction endonuclease cleavage sites were included in the coding sequence without altering the encoded protein sequence. The synthetic TAT coding sequence was fused to a translation start signal and placed under SV40 early transcriptional control. Co-transfection of the TAT-encoding synthetic gene together with a reporter gene (chloramphenical acetyl transferase or beta-galactosidase) linked to an HIV LTR confirmed that the synthetic gene product exhibits similar activity to TAT expressed from HIV genomic DNA in the transactivation of the LTR. TAT mRNA prepared by cell-free transcription of the synthetic TAT coding sequence was also shown to produce functional TAT following microinjection into HeLa-derived cells containing an integrated reporter gene with the HIV LTR linked to beta-galactosidase.
...
PMID:Chemical synthesis and expression of a gene encoding HIV-1 TAT protein. 254

The BMLF1 region of the Epstein-Barr virus (EBV) genome and the immediate-early (IE) region of human cytomegalovirus (HCMV) both encode proteins which can trans-activate heterologous promoter/chloramphenicol acetyl transferase (CAT) constructs, including a human immunodeficiency virus type-1 promoter/CAT construct. We demonstrate here that this trans-activation by the EBV BMLF1 gene product, which we have previously shown to be largely post-transcriptional, is reporter gene dependent. In contrast, trans-activation by the HCMV-IE gene product(s), previously shown to be mediated at the RNA level, is seen regardless of whether CAT, human growth hormone, or beta-galactosidase is used as the reporter gene. Mutational analysis revealed no specific cis-acting sequences within the HIV-1 promoter which were required for trans-activation by the HCMV-IE gene product(s).
...
PMID:Disparate effects of two herpesvirus [corrected] immediate-early gene trans-activators on the HIV-1 LTR. 255 54

Expression of the human immunodeficiency virus (HIV) rev protein is required for expression of virus structural proteins. Site-directed mutagenesis was used to localize regions important for Rev function. We found that proteins with single amino acid substitution mutations concentrated within the amino termini and midportion of Rev were for the most part nonfunctional. Indirect immunofluorescence revealed that Rev was localized predominantly in the nucleolus. However, a deletion mutant that lacked the basic stretch of amino acids comprising residues Arg-Arg-Arg-Arg-Trp accumulated in the cytoplasm and was no longer functional. Consistent with this observation, a beta-galactosidase fusion protein containing this basic rich peptide at its amino termini was targeted to the nucleus. These observations indicate that the HIV rev protein has a distinct nuclear localization sequence and suggest that Rev-mediated regulation of gene expression involves nuclear events.
...
PMID:Structural and functional characterization of the human immunodeficiency virus rev protein. 265 90

A human mitochondrial protein, designated P1 (63 kilodaltons [kDa], shows extensive sequence homology (47% identical residues and an additional approximately 20% conserved changes) to the 65-kDa mycobacterial antigen. To understand the relationship of these proteins, the cross-reactivity of several monoclonal antibodies directed against the 65-kDa Mycobacterium leprae antigen towards human, Chinese hamster, chicken, and bacterial cells has been examined. A number of antibodies (Y1-2, ML 30-A2, and F47-9-1) were found to cross-react with a 63-kDa antigen in vertebrate cell extracts and stained mitochondria in immunofluorescence studies. Some of these antibodies also reacted with a P1-beta-galactosidase fusion protein in recombinant Escherichia coli cells, expressing part of the human P1 protein. These results provide strong evidence that P1 is the mammalian homolog of the 65-kDa antigen. The human P1 protein also shows significant similarity (P less than 0.001) to a number of other bacterial and viral proteins including the pol polyprotein of human immunodeficiency viruses and the penicillin-binding protein of Neisseria gonorrhoeae. The observed similarity between human P1 protein and the major antigenic proteins of pathogenic organisms (e.g., 60- to 65-kDa mycobacterial antigen) suggests its possible involvement in autoimmune diseases (e.g., rheumatoid arthritis) by antigenic mimicry.
...
PMID:Immunological characterization of a human homolog of the 65-kilodalton mycobacterial antigen. 266 87

We have tested the functional compatibility between rev protein of human immunodeficiency virus type I (HIV-I) and rex protein of human T-cell lymphotropic virus type I (HTLV-I). Each protein recognized the other's cis-acting sequence, albeit at reduced levels. Both proteins localize predominantly in the nucleolus. We have identified a new nucleolar-targeting signal in rev protein, which was homologous to that of rex protein. The sequence [35-RQARRNRRRRWRERQR-50] in rev protein, when fused to the amino-terminus of beta-galactosidase, directed the hybrid protein to the cell nucleolus. A deletion mutant which lacks several amino acid residues within the signal failed to function in the CAT assay system. These results demonstrate that the nucleolar targeting signals are essential for the functions of Rev and Rex.
...
PMID:Functional similarity of HIV-I rev and HTLV-I rex proteins: identification of a new nucleolar-targeting signal in rev protein. 278 17

A novel expression system based on coinfection of cells with two recombinant vaccinia viruses has been developed. One recombinant vaccinia virus contained the bacteriophage T7 RNA polymerase gene under control of a vaccinia virus promoter. The second recombinant vaccinia virus contained a target gene of choice flanked by bacteriophage T7 promoter and termination sequences. Maximum expression of the target gene occurred when cells were infected with 10 PFU of each recombinant virus. Although T7 RNA polymerase synthesis began shortly after infection, the target gene was not expressed until late times and was largely inhibited when DNA replication was blocked. Target gene transcripts were analyzed by agarose gel electrophoresis and had the predicted size. With this system, Escherichia coli beta-galactosidase, hepatitis B virus surface antigen, and human immunodeficiency virus envelope proteins were made. In each case, the level of synthesis was greater than had previously been obtained with the more conventional recombinant vaccinia virus expression system.
...
PMID:Use of a hybrid vaccinia virus-T7 RNA polymerase system for expression of target genes. 311 59

Serologic testing for human immunodeficiency virus type 1 (HIV-1) is currently based on enzyme linked immunosorbent assay (ELISA) as screening method. Positive ELISA-results have to be confirmed by at least one second procedure such as Western blotting or immunofluorescence. To obtain new diagnostic reagents for confirmatory testing, we expressed viral antigens in procaryotic systems. Peptides representing epitopes of structural core (gag)- and envelope (env)-proteins of HIV were produced in E. coli as stable immunogenic beta-galactosidase fusion proteins. Recombinant proteins were taken for immunoblot-assays. The results of Western blotting with those fusion proteins were in general comparable with conventional ELISA, immunofluorescence, immunoblot with cell-culture derived virus and commercially available ELISA tests based on recombinant proteins. Immunoblots using recombinant transmembrane protein (gp41) derived polypeptide were more sensitive than the conventional procedure with purified virion proteins. Western blotting with recombinant fusionproteins provide reliable and inexpensive serodiagnostics without handling of infectious cell cultures.
...
PMID:[Serologic AIDS diagnosis with polypeptides obtained by genetic technics of the human immunodeficiency virus (HIV-1)]. 332 45


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---